ABSTRACT
Polypyrrole (PPy) films modified with copper species were used for disinfection of well water contaminated with Escherichia coli (E. coli). For that purpose a laboratory-scale continuous flow system with a parallel plate flow chamber configuration was implemented operating under laminar flow. Three flow rates were considered. The testing conditions did not affect the morphology of the modified PPy films, even after 5 h of continuous use at the largest flow rate examined. The results show that the bacteria killing process can be described by a first-order kinetic law at all Reynolds numbers. As the flow rate increases, the concentration of Cu species released from the electrodes enhances, accelerating the disinfection process. Re-inoculation and Cu-recharging tests showed bactericidal effects very similar to those displayed by the freshly prepared electrodes. It is concluded that PPy/Cu-modified electrodes installed in the laboratory-scale continuous flow system are effective for the water disinfection process.
Subject(s)
Escherichia coli , Polymers , Water Microbiology , Water Purification/methods , Electrodes , Pyrroles , WaterABSTRACT
Gallium, zinc and cobalt species were immobilized in hollow rectangular-sectioned microtubes of polypyrrole (PPy) electrosynthesized on Nitinol (NiTi) alloy by means of two different methods. One of them involved the immobilization after the PPy electropolymerization and the other one during the electrosynthesis process. The antibacterial activity of the coating against Escherichia coli (E. coli) was evaluated and the best results were obtained with gallium species. Characterization results demonstrated that gallium is incorporated into the PPy matrix as Ga3+ ions. The PPy film with gallium species incorporated during the electropolymerization exhibited a good corrosion protection performance.
Subject(s)
Alloys/chemistry , Anti-Bacterial Agents/chemistry , Metals/chemistry , Polymers/chemistry , Pyrroles/chemistry , Anti-Bacterial Agents/pharmacology , Cations/chemistry , Cobalt/chemistry , Escherichia coli/drug effects , Gallium/chemistry , Microscopy, Electron, Scanning , Photoelectron Spectroscopy , Zinc/chemistryABSTRACT
Copper species immobilization in hollow rectangular-sectioned microtubes of polypyrrole (PPy) electrosynthesized on 316L stainless steel was carried out using two different methods. One of them involved the immobilization after the PPy electropolymerization and the other one during the electrosynthesis process. The electrodes modified with copper species were rotated at different speeds in well water under open-circuit potential conditions. The release of copper species from the PPy matrix and the antibacterial activity against Escherichia coli were analyzed. The obtained results demonstrate that the amount of copper species released as well as the bactericidal effects against E. coli increases with rotation speed. The PPy coating modified with copper species after the electropolymerization reaction exhibited the best performance in terms of antibacterial activity and corrosion protection. These electrodes were tested in a lab-scale continuous flow system for well water disinfection.
Subject(s)
Anti-Bacterial Agents/analysis , Copper/analysis , Disinfection/methods , Escherichia coli/drug effects , Polymerization , Polymers , Pyrroles , Water Microbiology , Anti-Bacterial Agents/pharmacology , Copper/pharmacology , Corrosion , Electrodes , Escherichia coli/growth & development , Stainless Steel , Water Quality , Water WellsABSTRACT
The electrosynthesis of polypyrrole films onto Nitinol from sodium salicylate solutions of different concentrations is reported. The morphology and corrosion protection properties of the resulting coatings were examined and they both depend on the sodium salicylate concentration. The immobilisation of silver species in PPy films constituted by hollow rectangular microtubes was studied as a function of the polymer oxidation degree. The highest amount of silver was deposited when the coated electrode was prepolarised at -1.00V (SCE) before silver deposition, suggesting an increase in the amount of non-oxidised segments in the polymer. Finally, the antibacterial activity of the coating against the Gram positive Staphylococcus aureus and Staphylococcus epidermidis bacteria was evaluated. Both strains resulted sensitive to the modified coatings, obtaining a slightly better result against S. aureus.
Subject(s)
Alloys/chemistry , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Polymers/chemistry , Pyrroles/chemistry , Silver/chemistry , Corrosion , Electrochemistry/methods , Electrodes , Oxidation-Reduction , Sodium Salicylate/chemistry , Solutions/chemistry , Staphylococcus aureus/drug effects , Staphylococcus epidermidis/drug effectsABSTRACT
Nitinol (equiatomic Ni and Ti alloy (NiTi)) substrate was modified using a coating system formed by a self-assembled film of alkylsilane compounds (propyltrichlorosilane (C3H7SiCl3) or octadecyltrichlorosilane (C18H37SiCl3)) and polypyrrole (PPy) doped with sodium bis(2-ethylhexyl) sulfosuccinate (Aerosol OT or AOT). The combination of alkylsilanes and the presence of a voluminous molecule like AOT entrapped into the PPy films improve the pitting corrosion resistance of the substrate in chloride solution. The best performance was achieved with the longest alkylsilane chains, where the PPy film remains adhered to the underlying coating after a pitting corrosion test.
